High frequency switch

ABSTRACT

A high frequency switch particularly adapted for use in an attenuation box having a switch arm formed of sheet metal with spaced, parallel strip portions interconnected by a web portion. The ends of the switch arm have contact tongues extending therefrom with a pair of contact tongues on one end having means for pivotally connecting to a conductor having a pair of parallel surface.

United States Patent [1 1 Sonnberger 51 Aug. 22, 11972 [54] HIGH FREQUENCY SWITCH 3,155,782 11/1964 Wilson, Jr ..200/1l TC [72] Inventor: Hanfried Smmberger, Ottobrunn, 3,382,340 5/1968 Moodie et a1. ..200/ 166 E Germany P E H O J nmary xammer-- ones [73] Asslgnee' Rohde & Schwarz Assistant Examiner-Robert A. Vanderhye [22] Filed: April 8, 1970 I Attorney-Hill, Sherman, Meroni, Gross & Simpson 21 A l. N 26,531 1 pp 0 57 ABSTRACT [30] Foreign Application p i m A high frequency switch particularly adapted for use in an attenuation box having a switch arm formed of Apl'll 17, Germany Sheet p parallel Strip portions intep connected by a web portion. The ends of the switch g g ggg Q g 2g arm have contact tongues extending therefrom with a 58 Field 0;;;;5IIIII.1"2'66/153 s 162 166 E 6 0, Pair Of Contact mngues one end having means for 200/6 BB 179 11 6 6 A, 6 pivotally connecting to a conductor having a pair of parallel surface. [56] References Cited 4 Claims, 1 Drawing Figure UNITED STATES PATENTS 2,747,060 5/ 1956 Ballou ..200/ 162 X 1 1 7 S1 2 3 D2 54 3 K2 HIGH FREQUENCY SWITCH BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to the high frequency switch utilizing the motor as an actuating means, and an attenuating box utilizing the high frequency switch.

2. Prior Art Various structures for high frequency switches for conductors of attenuation boxes are known. One type of structure has a switch arm constructed in the form of a disk of insulating material which is rotated about a central axis and carrys conducting strips on both faces. The ends of these conducting strips cooperate with terminals of a conductor which are disposed at the periphery of the disk. Examples of these structures are shown in US. Pat. No. 2,855,471 and German Pat. No, 1,004,251. However, the structures utilizing a rotating disk have a relatively large mass and consequently are relatively heavy and cannot be rapidly moved between switching positions.

A second type of switch structure which is disclosed in the German Pat. No. 962,990 utilizes a single strip portion pivotally attached to the end of one conductor which is disposed on a base plate. The strip portion is movable from an open position to a position contacting an end of a second conductor in an endwise relationship to complete the electrical connection. In such a switch construction, the contact obtained is relatively poor and it is difficult to obtain desirable impedance requirements for the switching structure.

SUMMARY OF THE INVENTION The present invention provides a high frequency switch which can be switched between terminals very rapidly and practically without chatter or bounce, and which switch achieves a reliable contact with desirable impedance characteristics which characteristics make the switch suitable for use in attenuation boxes.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is illustrated in the FIGURE which has portions broken away for purposes of illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENT In an attenuation box having two parallel plates, the distance between the plates is predetermined for various reasons. For example, with an attenuating member incorporated between the plates to be switched by switches, as illustrated, the space inbetween the plates is determined by the size (thickness) of the attenuating member and by the requirements that the attenuating member should be arranged correctly between the two plates from the characteristic impedance point of view.

The space inbetween the plates is also determined by the size of the high frequency sockets mounted at the edge of the plate which sockets provide connecting means for coaxial conductor that is to be joined to the attenuation box. The change in cross section between an outer conductor of the coaxial conductor and the conductor system of the box which system is formed by the parallel plates must be kept as small as possible in order to avoid reflection errors.

Assuming the space of 10mm between the plates is necessary to satisfy the above-mentioned requirement and, as hereto been normal, at small strip line or inner conductor of about 1mm thickness is employed, the inner conductor must have a width of about 10mm to maintain the characteristic impedance requirements of the inner conductor. To provide a switch structure for the inner conductor of a known structure for example, a simple switch arm in the form of a pivoting sheet metal strip or arm, the width of the arm to maintain the desired impedance characteristic would be such that the switch structure would result in a very space consuming arrangement and the fixed contacts would not be arranged in a small mutual separation as is desired for reasons of economy and space.

. The principles of the present invention overcome the difficulties by forming the switch arm from sheet metal which has been bent to provide a pair of spaced, parallel strip portions interconnected by a web portion. The inner conductor is provided with parallel spaced surfaces and preferably is also formed of sheet metal with the two parallel spaced surfaces being interconnected by a web portion. For example, if the parallel strip portions are only 3mm wide, the spacing therebetween can be reduced to about 5mm which is the height of the interconnecting web. Thus, the switch arm can be easily sandwiched between a pair of plates having a spacing of 10mm without destroying the desired impedance characteristics.

Referring to the Figure, an attenuation box having three attenuating members D D and-D sandwiched between two parallel plates 1 and 2 which are separated a predetermined distance 0. Connected to the box are coaxial plugs K and K with the outer conductor of the coaxial line being electrically connected to the parallel plates 1 and 2. The inner conductor of the coaxial line is connected to an inner conductor or strip line B which is disposed in a meandering path between the two plugs K and K As illustrated, the inner conductor B is formed of seven separate sections such as B, and B which are interconnected by individually actuated switches S through S with the switch S being actuated to connect the section B to the section B and the switch S connecting the section B to the next adjacent conductor section.

Each of the sections such as B, and B are formed of sheet metal such as illustrated has a U-shaped cross section with a pair of spaced strips 3 forming parallel spaced surfaces which are interconnected by a web 4. Adjacent the ends of each of the sections such as B a portion of the web is removed to provide a pair of tongues or projecting contact portions 10.

To provide a switch such as S to coact with the strip portion B,, a switch arm 6 is formed from a sheet of spring sheet metal into a U-shaped cross section with strip portions 8 which are spaced apart in a parallel arrangement and are interconnected by a web portion 9. The web portion 9 is removed adjacent each of the ends to provide contact tongues with one end pivotably connected by means such as a pin 7 to the projecting ends of the strip portions 3 of a conductor section such as 8,. With the tongue of the arm 6 overlying the contact portions on the conductor section B a good wiping contact is maintained.

Each of the attenuating members D is made up of three resistors W arranged in a known manner such as a Pi circuit. Each of the attenuating members such as D are provided with a pair of terminals 12 each of which has a pair of spaced projecting contact strips or tongues 11 to coact with the tongues of the switching arm 6.

To actuate the switch such as 8,, the switching arm 6 is connected to a lever 14 preferably made of insulating material which connection can be a projection received in a hole in the lower strip portion 8 of the switch arm 6. The lever arm 14 is mounted on a shaft 15 of an actuating means preferably a motor 20, however the switch could be manually or magnetically actuated.

The switches S to S are of the same construction as switch S and each of the switches is provided with an actuating means such as the motor 20.

As mentioned above, the two parallel plates 1 and2- of the attenuation box have a spacing a of approximately 10mm. The spaced strips 3 of the inner conductor B have a width b of about 3mm and the web 4 intercon necting the strips 3 has a width to provide a separation c between the strip portions of about 5mm. The inner conductor B is held by insulating supports 13 which have a step portion to support the conductor about 2.5mm from the surface of the lower plate 2 and a pin portion which is received with a force fit in aligned apertures provided in the strips 3. The U-shaped section of the inner conductor is bent from a sheet of metal having a thickness of 0.5 mm.

The actuation of the switch arm 6 between a position in contact with the contacts 1 1 of the terminal 12 and a position in contact with the contacts of the strip section 13 is preferably accomplished by the motor 20. By selectively moving both switches S and S to engage the terminals 12 of the attenuating member D the strip portion B is electrically insulated from the inner conductor and the attenuating member D, is electrically connected in the strip line. A like situation occurs when switches S and 8., are energized to selectively interconnect the attenuating means D or to selectively disconnect that attenuating means. Switches 8,, and S function to selectively interconnect and disconnect the attenuating member D The switches of each pair can be simultaneously actuated by means of a programmer to selectively place the desired attenuating member into the circuit.

To avoid contact bounce or chatter as the switches such as S move from one switch position to the other switch position, an actuating means such as motor 20 can be provided. The motor 20 has an armature which is connected to the drive shaft with the armature and drive shaft being rotatably supported in a motor housing 24. Disposed in the housing is a ring 21 which is free to rotate with respect to the drive shaft 15 and is frictionally supported within the housing. A lost motion connection interconnects the ring 21 to the housing 24 and is illustrated as being formed by a projection formed by a peg 22 mounted on the ring 21 which is slidably received in an elongated arcuate slot 23 in the housing or cover 24. The slot is of a length to allow a relative angular movement of 1 to 3 between the ring 21 and the housing 24.

The ring 21 has a moment of inertia about the axis of rotation of the shaft 15 which is substantially equal to the combined moment of inertia of the shaft 15, the armature and the moving parts of the switch 8,. To interconnect the ring 21 to the drive shaft 15, a second lost motion connection comprising a pair of annularly spaced projections formed by pegs 25 and 26, respectively, extending downwardly from a surface of the ring 21 and are engaged by a finger 28 which is preferably made of a synthetic resin and is carried by the shaft 15. The annular space in between the pegs 25 and 26 corresponds to the angular range of movement of switch arm 6 while moving from one switch position to the other which range is approximately 90. The ring 21 is also provided with spring means that increases the friction between the ring and the housing. As illustrated the spring means comprises a hoop 27 of steel wire inserted in a groove 29 formed in the upper face of the ring 21. The hoop is held in the groove by the extensions on the pegs 25 and 26and in its held-in position bulges outwardly beyond the edge of the groove. In the assembled condition, the outwardly projecting steel wire 27 rubs against the inside surface of the housing 24 of the motor to retard movement of the ring with respect to the housing.

As the switch moves toward a position to connect the arm 6 to the contacts 10 and the arm 6 engages the contacts 10, the finger 28 strikes the peg 25 on the ring 21 which is freely rotatable with respect to the shaft 15. According to physical laws governing the coming together of two bodies of about the same inertia, the shaft 15 and accordingly the switch arm are rapidly decelerated by the addition of the inertia of the ring 21. The wiping movement of the contact tongues of the arm 6 engaging the contacts projecting tongues 10 of the conductor line B apply a resistance tofurther angular movement of the arm 6 which comes to a standstill as the ring 21 continues to move. However, the movement of the ring 21 is immediately braked by the spring means formed by the wire steel loop 27 bearing frictionally against the housing 24. Finally, the ring comes to a standstill with the peg 22 engaging the edge of elongated slot or hole 23.

In switching in the opposite direction, the armature and shaft 15 are free to rotate through the angle of approximately 90 before contacting the peg 26. At the time of contacting the peg 26, the tongues of the switch arm 6 are engaging the contacts 11 of the terminal 12 and the change in the moment of inertia of the rotating bodies causes the rapid deceleration of the shaft 15. Due to the lost motion connection formed by the projection 22 and the slot 23, the ring 21 can move a slight sheet metal so that its end portions or tongues which are received between the contacts 10 or 11 are urged resiliently apart to insure a good wiping engagement with the contacts 10 of the conductor section and the contacts 11 of the terminals 12. The sections such as B and B of the conductor B can be formed of various cross-sectional profiles such as a double T cross-section or a hollow section with a rectangular cross-section. The conductors can also be made of solid rectangular cross-section and can be formed of any suitable material such as brass or silver if desired.

Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. A high frequency switch for use in a strip line disposed between a pair of parallel plates for selectively interconnecting a pair of conductors of the strip line with each conductor having spaced parallel strips, comprising a switch arm being formed of sheet metal and having a pair of spaced, superimposed strip portions interconnected by a web portion, each of the strip portions having contact tongues at each end, the contact tongues at one end of said arm having means for pivotally connecting said arm to one of said conductors so that said contact tongues at said one end are in continual electrical contact with said one conductor as said arm is pivotally'moved between switching positions, and actuating means connected to said arm adjacent said one end for moving the arm between switch positrons.

2. A high frequency switch according to claim 1, wherein the arm has substantially a U-shaped cross section.

3. A high frequency switch according to claim 1, wherein said means for pivotally connecting includes a pin extending through said contact tongues at said one end of said arm and the end of the strips of said one connector.

4. A high frequency switch according to claim 1, wherein said actuating means comprises a motor having a drive shaft carrying a lever arm engaging a strip portion of the switch arm. 

1. A high frequency switch for use in a strip line disposed between a pair of parallel plates for selectively interconnecting a pair of conductors of the strip line with each conductor having spaced parallel strips, comprising a switch arm being formed of sheet metal and having a pair of spaced, superimposed strip portions interconnected by a web portion, each of the strip portions having contact tongues at each end, the contact tongues at one end of said arm having means for pivotally connecting said arm to one of said conductors so that said contact tongues at said one end are in continual electrical contact with said one conductor as said arm is pivotally moved between switching positions, and actuating means connected to said arm adjacent said one end for moving the arm between switch positions.
 2. A high frequency switch according to claim 1, wherein the arm has substantially a U-shaped cross section.
 3. A high frequency switch according to claim 1, wherein said means for pivotally cOnnecting includes a pin extending through said contact tongues at said one end of said arm and the end of the strips of said one connector.
 4. A high frequency switch according to claim 1, wherein said actuating means comprises a motor having a drive shaft carrying a lever arm engaging a strip portion of the switch arm. 